1. Field of the Invention
The present invention relates to semiconductor devices. In particular, the present invention relates to a semiconductor device suitable for application to a solid-state imaging device.
2. Description of the Related Art
Typical examples of a solid-state imaging device include a CCD (Charge Coupled Device) image sensor of a charge transfer type and a CMOS (Complementary Metal Oxide Semiconductor) image sensor for reading data by specifying an X-Y address. These solid-state imaging devices are similar to each other in that a light-receiving section formed of a photo diode is provided for each of pixels two-dimensionally disposed and light entering this light-receiving section is converted to electrons.
In general, most solid-state imaging devices have a structure in which light enters from a side where a wiring layer is formed. In a solid-state imaging device of this type, sensitivity may be degraded by the wiring layer that prevents the incident light from entering pixels by reflection. Moreover, with reflected light from the wiring layer entering adjacent pixels, color mixing may occur.
To get around these problems, in the related art, a solid-state imaging device of a so-called back-illuminated-type is suggested (refer to Japanese Unexamined Patent Application Publication No. 2005-209677) in which light enters from a side opposite to the side where the wiring layer is formed.